Reliquary theca with relics of Saint Petronius (San Petronio), Bishop of Bologna

Round yellow-metal glass-fronted reliquary theca housing a first-class ex ossibus  (of the bone) relic of the Saint Petronius of Bologna. The relic is affixed to a red silk ground and identified in Latin on typeset cedula label as Osso S. Petronio Ves. (of the bone of Saint Petronius, Priest).  On the back, under a protective cap, the theca is secured with a seal of red Spanish wax bearing an imprint of a coat of arms of a Roman Catholic Archbishop.

Saint Petronius (Italian: San Petronio) (†ca. 450 AD) was bishop of Bologna during the fifth century. He is a patron saint of the city. Born of a noble Roman family, he became a convert to Christianity and subsequently a priest.In the twelfth century appeared a legendary life of the saint, whose relics were discovered in 1141. Shortly afterwards a church was erected in his honour at Bologna; a second, San Petronio Basilica, planned on a large seal, was begun in 1390. In 2000, his relics were moved from Santo Stefano to the Basilica of San Petronio. The feast of St. Petronius is celebrated on 4 October.